Research related to metal-organic frameworks (MOFs) as well as coordination polymers (CPs) (for a perspective understanding of the differences between the terms CP, MOF and hybrid organic-inorganic materials, see Biradha et al., Cryst. Growth Des., 2009, 9, 2969-2970) has been treated with overwhelming interest by the scientific community of chemists and physicists due to tunable properties of these molecular assemblies by controlling their growth, size and shape, and their potential applications in the fields of catalysis, gas storage, separation, recognition and purification, optics, sensors, etc. (Zhao, et al., Science, 2004, 306, 1012; Yaghi, et al., Nature, 2003, 423, 705; Seo, et al., Nature, 2000, 404, 982; Kitagawa, et al., Angew. Chem., Int. Ed. 2004, 43, 2334; Evans, et al., Acc. Chem. Res. 2002, 35, 511; Rowsell, et al., Angew. Chem., Int. Ed. 2005, 44, 4670; Tabellion, et al., J. Am. Chem. Soc. 2001, 123, 7740; Lei, et al., J. Phys. Chem. C. 2007, 111, 11291; Zhao, et al., Inorg. Chem. 2008, 47, 7133; Chen, et al., Acc. Chem. Res. 2010, 43, 1115). It was in 1964 that J. C. Bailar defined the term “coordination polymer” (Bailar, J. C., Jr Prep. Inorg. React. 1964, 1, 1-57) and a wide variety of techniques such as solvothermal (Jung, et al., Angew. Chem., Int. Ed. 2008, 47, 2049-2051; Ni, et al., J. Am. Chem. Soc. 2006, 128, 12394-12395), precipitation (Oh, et al., Nature 2005, 438, 651-654; Oh, et al., Angew. Chem., Int. Ed. 2006, 45, 5492-5494; Sun, et al., J. Am. Chem. Soc. 2005, 127, 13102-13103; Park, et al., J. Am. Chem. Soc. 2006, 128, 8740-8741; Wei, et al., Chem. Mater. 2007, 19, 2987-2993) and reverse microemulsion (Rieter, et al., J. Am. Chem. Soc. 2006, 128, 9024-9025) methods have been employed in the generation of shape selective nano and micro structured CPs (Wang, et al., Chem. Commun. 2009, 5457-5459; Shi, et al., Chem. Commun. 2011, 47, 5055-5057; Liu, et al., Cryst. Growth Des. 2010, 10, 790-797; Lu, et al., J. Mater. Chem. 2011, 21, 8633-8639; Li, et al., J. Mat. Chem. 2011, 21, 17946-17952; Cho, et al., J. Am. Chem. Soc. 2008, 130, 16943-16946).
Structural uniformity is a prerequisite for many real-world applications including oriented fabrication of various materials, often in size-confined regimes (Tuxen, et al., J. Am. Chem. Soc. 2013, 135, 2273-2278). At the same time, structural diversity can lead to control of desired physical and chemical properties (Noorduin, et al., Science 2013, 340, 832-837; Pevzner, et al., Nano Lett. 2012, 12, 7-12; Whitesides, et al., Science 2002, 295, 2418-2421; Masoomi, et al., RSC Adv., 2013, 3, 19191-19218; Gu, et al., Nano Lett. 2012, 12, 6385-6392). Molecular self-assembly allows the construction of composite superstructures with unique structure and properties. Size and shape confined synthesis of such composites are advantageous for their intrinsic and complex multi-functionalities, allows addressing properties of individual components and the combination thereof, and the possibilities of their spatial integration into devices and onto surfaces (Carné-Sánchez, et al., Chem. Eur. J. 2014, 20, 5192-5201). Needless to say “structure dictates function at all scales” (Tao, et al., Small 2008, 4, 310-325).
Due to their unique, often porous structures and special properties achieved through synthetic tunability, MOFs have been actively studied over the last few decades (Furukawa, et al., Science 2013, 341, 1230444; Cook, et al., Chem. Rev. 2013, 113, 734-777; Long, et al., Chem. Soc. Rev. 2009, 38, 1213-1214). However, control over their spatial topologies at the micro and nano levels is still limited and difficult to achieve (Stock, et al., Chem. Rev. 2011, 112, 933-969; Sindoro, et al., Acc. Chem. Res. 2014, 47, 459-469). Many variables, e.g., anions, solvents, and electronic configuration, play a key role in the formation of geometrically well-defined and uniform shapes. Thus far, the shapes of MOFs are limited to simple polyhedra (Sindoro et al., Acc. Chem. Res. 2014, 47, 459).